Electron discharge device and associated circuits



Dec. 11, 1951 H. c. THOMPSON 2,578,458

ELECTRON DISCHARGE DEVICE AND'ASSOCIATED CIRCUITS Filed Ma 28, 1949 35 our/ 07% INVENTOR GOA/$72M HARRY C. THOMPSON AMPl/TUDE VOUZIGffatented Dec. 11, 1951 ELECTRON DISCHARGE DEVICE AND ASSOCIATED CIRCUITS Harry C. Thompson, Chester, Vt., assignor to Radio Corporation of America, acorporation of Delaware Application May 28, 1949, Serial No. 96,056

12 Claims.

This invention relates to electron discharge devices and associated circuits, and more particularly to such devices of the beam deflection type.

Many devices and circuits'are known by which the frequency of a signal can be multiplied. However, there is no satisfactory means available at present for frequency division.

In accordance with my invention, the decrement of oscillations in a free circuit periodically energized by a beam pulse in a double deflection beam device and associated circuit is the basis for frequency division. Means is provided for maintaining constancy of periodic voltage across one pair of deflection plates by balancing the efiect of one set of beam pulses having a regenerative effect against another set 180 degrees therefrom and having a degenerative effect. The latter feature is also applied to maintaining a constant output voltage with varying input amplitude or frequency in a single deflection beam device.

The principal object of my invention is, therefore, to provide an electron discharge device which can serve as a frequency divider. Another object is to provide a double-deflection electron discharge device with means for maintaining constancy of voltage across one pair of deflection plates. Still another object is to provide a singledeflection beam device for maintaining constant voltage of an applied signal of varying amplitude and/or frequency. A further object of the invention is to provide an improved beam deflection device.

These and other objects and advantages of my invention will be apparent from the following detailed description taken in connection with the annexed drawing, in which:

Figure 1 is a perspective view of an electron discharge device embodying my invention;

Figure 2 is a schematic view partly in axial section of the device of Figure l and an associated circuit; and v Figure 3 is a schematic view partly in axial section of a modification embodying my invention.

Referring to Figures 1 and 2, in which like parts are identified by the same reference numeral, the electron device comprises an elongated envelope I along the axis of which are mounted a cathode 3, a beam-forming electrode '5, a first pair of deflection plates 1 and 9, a second pair of deflection plates H and I3 rotated ninety degrees with respect to the first pair I and 9, and a target structure l5. The target structure comprises a circular planar electrode or plate I! having a rectangular aperture 20 located on one side of the vertical axis of the plate H, as shown in Figure 1. Rectangular apertures l9 and 2| are provided along the vertical axis of the plate ll, above and below the aperture 2i], as shown. Collector electrodes or plates 23, 24 and 25 are mounted behind the apertures I9, 20 and 2|, respectively, to collect electrons which pass through the apertures. The outer collector plates 23 and 25- are connected together either inside or outside the envelope. Direct current potentials for the various electrodes may be obtained from a potential divider 26 connected to a suitable voltage source. A suppressor electrode 21, connected to the cathode 3 and having apertures registering with the collector plates 23, 2t and 25, may be interposed between the plate I! and the collector plates for suppressing secondaries emitted by the collector plates. The beam is centered by suitable direct current biasing means (not shown) so that part of it passes through the aperture 20 in its vertical travel.

As indicated in Figure 2, an input voltage of frequency f is applied to the plates 1 and 9, as by means of a transformer 29 and input circuit 30. This voltage deflects the electron beam from the cathode 3 vertically across plate ll. When the beam passes through aperture 20 to collector 24 a voltage is built up in circuit 3| which is in quadrature with that applied to the plates 7 and 9, due to the location of collector 24 midway of the vertical travel of the beam. This quadrature voltage is applied to the plates H and I3 to deflect the beam horizontally. If the beam current is sufficient, oscillation of circuit 3| builds up to'give a horizontal or transverse deflection equal, in a particular case, to the vertical deflection. The beam will then begin to trace a circular path 33 on plate ll. However, since the beam no longer passes through aperture 20, the horizontal deflection voltage decreases in accordance with the predetermined decrement of circuit 3|, causing the beam to trace elliptical paths of decreasing horizontal width until the beam again passes through aperture 20. The circuit 3| is thus again excited to restore the deflection voltage on plates H and I3, whereupon the whole operation is repeated. With the orbits shown in Figure 1, the beam passes through aperture 20 only once in four cycles of the input voltage of frequency 1. Therefore, the output circuit 35, which is in series with the circuit 3|, receives impulses of frequency 1 divided by four. To bring about the described "3 circular and elliptical paths associated behavior of the beam, the circuit 3| is tuned to the input frequency f. If a relatively high order of frequency division is desired, the tuned circuit 3| may be replaced by a suitable quartz crystal. An inductance 31 is inserted between the collector 24 and circuit 3i so as to delay the rise of potential on the deflection plates H and 13 by a small fraction of a cycle represented by the width of aperture 20. In some cases it may be necessary or desirable to interpose one or more stages of amplification between the circuit 31' and the plates II and I3. The feature which distinguishes this device from devices employing a single pair of deflection plates is the separation of the orbital paths by a finite distance whereby the feedback impulse to circuit 3| is made to take place only at an integral number of cycles from the starting cycle and at a particular invariable phase of such impulse cycle.

The successful operation-oi the device depends upon the constancy of amplitude of the voltage between the deflecting plates 1 and 9 over a range which becomes narrower the greater the frequency reduction attempted. This i because the charge given to collector 24 per impulse varies inversely as the amplitude of the vertical deflection. To maintain constancy of amplitude of the vertical deflection voltage, the apertures l9 and 2i are provided, with the outer edge of aperture l9 and the inner edge of aperture 2| being equally distant from the midpoint of vertical beam travel, that is, from the middle of aperture 20. In other words, the distance A equals the distance B in Figure 1. Normally a portion of the beam at its upper limit of travel passes through upper aperture l9 to collector 23 to transmit a voltage pulse to the lower deflecting plate 9 in such phase relation to the voltage across plates and 9 as to supply energy to the input circuit 38 and to tend to regenerate or increase the voltage which that circuit applies to plates 1 and 9. Likewise a portion of the beam at its lower limit of travel passes through lower aperture 2| to collector to transmit a voltage pulse to lower plate 9 but at 180 degrees from the aforesaid pulse, whereby energy is abstracted from the input circuit and there is a tendency to degenerate or decrease the vertical deflecting voltage. Momentary increase of maximum vertical deflection amplitude, due to an increase in the input voltage applied to transformer 29, thus causes the beam to miss the upper aperture l9 at its upper limit of travel and decrease the regeneration, and to enter the lower aperture 2| and increase the degeneration, both of which actions tend to prevent such increase of vertical deflection amplitude and to stabilize it near a particular value.

In Figure 3 the above-described process of Y stabilization of vertical deflection amplitude is applied to a device having a single pair of deflection plates in order to deliver an output of constant voltage amplitude with an input voltage of varying amplitude or frequency. This device may be termed a voltage limiter in contrast with familiar current limiters. The cathode 3, beamforming electrode 5 and the single pair of deflection plates 1 and 9 are the same as the corresponding elements in Figures 1 and 2. The target structure i5 comprises a planar electrode or plate ll" having apertures 59 and 2|, which may be rectangular as in Figure 1 if desired, provided therein above and below the axis of the undeflected beam. A single collector electrode or plate 39 is mounted behind the plate H in position to collect electrons passing through the 4 apertures l9 and 2|, and is connected to the lower plate 9. An apertured secondary electron suppressor electrode 21' may be interposed between the plate ll and collector 39. Direct current potentials for the electrodes are obtained from a potential divider 2s. The apertures l9 and 20' are so spaced from the axis of the undeflected beam that the distance A equals the distance B, as in Figures 1 and 2.

' The operation of the device shown in Figure 3 is substantially identical with that described above for Figures 1 and 2, insofar as the stabilization of the alternating voltage across the circuit 38' is concerned, and hence, it is not necessary to repeat the description here. An alternating voltage of constant amplitude may be obtainedfrom the circuit 35 by means of condensers 4i and 43, as indicated in Figure 3.

If'desired, the apertured electrodes 2? and 27 of Figures 1 and 3 may be utilized to produce electron multiplication of the currents of thecollector electrodes 23, 24, 25-and 39, instead of suppressing secondaries from the collector electrodes. Thus, in Figure 2 the electrode 21 may be connected to the plate IT, with the collector electrodes 23, 24 and 25 made secondary emissive and operated at suitably lower potentials than the electrodes I! and 21. If this is done, the phase reversal of currents due to the use of secondary emission necessitates reversal of the connections of the collector electrodes to the deflection plates, that is, the collector electrodes 23 and 25 must be connected to plate 1 instead of plate 9, and collector electrode 24 must be connected to plate I I instead of plate I3, in Figure 2.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only two specific applications for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is-employed without departing from the scope of my invention as set forth in the appended claims.

'1. An electrical system comprising means for supplying a beam of electrons along a predetermined beam -path,'means for collecting said beam, a pair of deflection plates interposed between said electron supplying -means and said collecting means and disposed on opposite sides of said beam path, means for applyinga periodic input voltage across said'deflection plates for laterally deflecting the beam across said collecting means, and means disposed in part in the path of the beam and responsive to a momentary change in the maximum amplitude of deflection of the beam for applying to said deflection plates a voltage pulse out of phase with said input voltage, said last-named means including an electrode forming a part of said beam'collecting means and a low impedance connection between said electrode and one of said deflection plates whereby the amplitude of deflection of said beam is stabilized near a given value.

2. An electrical system comprising means for supplying a beam of electrons along a predetermined *beam path, means for collecting said beam, a pair of deflection plates interposed between said electron supplying means and said collecting means and disposed on opposite sides of said beam path, means for applying a pcriodic input voltage across said deflection plates aevacss for laterally deflecting the beam acrossv said collecting means, said collecting means including a planar electrode disposed transversely of said beam path and having an aperture on the same side of said path as one of said deflecting plates and spaced from said path a distance greater than the normal deflection of said beam by said input voltage and collector electrode means positioned beyond said planar electrode in position to receive electrons of said beam through said aperture, and means connecting said collector electrode means to said one dew flecting plate, whereby an increase of the maximum amplitude of deflection resulting from an increase in maximum amplitude of said input voltage causes said beam to enter said aperture and impinge upon said collector electrode means, which in turn causes a decrease in' the potential of said one deflecting plate in opposition to said increase in maximum amplitude of the input voltage, thereby stabilizing the amplitude of deflection of the beam.

3. An electrical system comprising an electron discharge device having an elongated envelope containing a cathode, a beam-forming electrode adjacent said cathode for producing a beam of electrons along a predetermined beam path, a pair of opposed deflecting plates on opposite sides of said path and a collector electrode structure, spaced along the axis of the envelope in the order named, said collector electrode structure including a planar electrode disposed normal to the beam path and having a pair of apertures therethrough on opposite sides of the path and so disposed that the outer edge of one aperture is spaced from said beam path substantially the same distance as the inner edge of the other aperture and collector electrode means mounted beyond said planar electrode in position to receive electrons passing through said apertures, means connecting said collector electrode means to one of said deflecting plates, means for maintaining said planar electrode at a given positive potential relative to said cathode, means for maintaining said deflecting plates and said collector electrode means at a lower positive potential, and means for applying a periodic deflecting voltage across said deflection plates.

4. An electron discharge device comprising an elongated envelope containing a cathode, a beam-forming electrode, a pair of opposed deflection plates and a collector electrode structure, spaced along the longitudinal axis of said envelope in that order and defining a beam path, said collector electrode structure including a planar electrode disposed transversely of said beam path and having an aperture on the same side of said beam path as one of said plates and spaced from said path and collector electrode means positioned beyond said planar electrode in position to receive electrons of said beam through said aperture, means connected to said deflection plates for applying a periodic deflection voltage thereto during operation of said device, and .means connecting said collector electrode means to said one deflection plate, whereby during operation of said device an increase in maximum amplitude of said deflection voltage causes said beam to enter said aperture and apply an out of phase potential to said one deflection plate.

5. An electron discharge device comprising an elongated envelope containing a cathode, a beam-forming electrode, a pair of opposed deflecting plates and a collector electrode structure, "spaced along the longitudinal axis of said envelope in that order and defining a beam path, said collector electrode structure including a planar electrode disposed transversely of said beam path and having a'pair of apertures therethrough on opposite sides of the path and so disposed that the outer edge of one aperture is spaced from said beam path substantially the same distance as the inner edge of the other aperture and collector electrode means mounted beyond said planar electrode in position to receive electrons passing through said apertures, means connected to said deflection plates for applying a deflection voltage thereto during operation of said device, and means connecting said collector electrode means to one of said deflection plates, whereby during operation of said device a change in the amplitude of deflection due to a change in amplitude of said deflection voltage causes said beam to enter one of said apertures and apply a potential to said one of said deflection plates of such phase as to oppose the change in amplitude of said deflection voltage, to stabilize the latter near a given value.

6. An electrical system comprising means for supplying a beam of electrons along a predetermined beam path, means for collecting said beam, two separate deflection means positioned along said path between said electron supplying means and said collecting means for deflecting said beam laterally in two perpendicular planes, means for energizing one of said deflection means in accordance Witha periodic input voltage to deflect the beam in one'plane, means including said collecting means and responsive to said beam for generating a voltage pulse in quadrature with said input voltage during a portion of the beam travel in said one plane and for applying said voltage pulse to the other of said two deflection means to deflect the beam in the other of said two planes.

7. An electrical system according to claim 6, further comprising, means for stabilizing the amplitude of beam deflection in said one plane, said stabilizing means including means disposed in part in the path of the beam and responsive to a change in the amplitude of deflection in said one plane for causing a change in said one deflection means in a direction to oppose the change in amplitude.

8. A frequency dividing system comprising means for supplying a beam of electrons along a predetermined beam path, means for collecting said beam, two separate deflection means positioned along said path between said electron supplying means and said collecting means for deflecting said beam laterally in two perpendicular planes, means for energizing one of said two deflection means in accordance with a periodic input voltage of given frequency to periodically deflect the beam in one of said two planes, said collecting means including a planar electrode disposed transversely of the beam path and having a central aperture through which the undeflected beam is adapted to pass and a collector electrode positioned beyond said planar electrode in position to receive said beam when it passes through said aperture, a circuit connected across the other of said two deflection means, and means connecting said collector electrode to one side of said circuit to apply a deflecting potential thereto which is in quadrature with said input voltage when said beam passes through said aperature to deflect the beam in the other of said two planes, whereby said beam is caused to trace an integral number of closed orbits on said planar electrode before passing again through said aperture and thus produce an output voltage across said circuit having :a frequency equal to said given input 'frequency divided by said integral number.

9. A frequency dividing system according to claim 8, wherein said circuit is tuned to the frequency of said input voltage.

10. A frequency dividing system according to claim 8, further comprising means for stabilizing the amplitude of beam deflection in said one plane, said stabilizing means including a pair of apertures formed in said planar electrode on opposite sides of the beam path and said central aperture and so disposed that the outer'ed'ge of one aper ture is spaced from said beam path substantially the same distance as the inner edge of the other aperture, collector electrode means positioned beyond said planar electrode in position to receive electrons passing through said pair of apertures and means connecting said collector electrode means to said one of said deflecting means.

11. An electron discharge device having an elongated envelope containing a cathode, a beamforming electrode, a first pair of opposed deflection plates, a second pair of opposed deflection plates disposed at right angles to said first pair, and a collector electrode structure, spaced along the longitudinal axis of said envelope in that order and defining a beam path, said collector electrode structure including a planar electrode normal to the beam path and having an aperture located adjacent but spaced from the beam path and a collector electrode positioned beyond said planar electrode in position to receive said beam when it passes through said aperture, and means connecting said collector electrode to one of said second pair of deflection plates to apply a compensating deflecting potential thereto during operation of said device. a

12. An electron discharge device having an elongated envelope containing a cathode, a beamforming electrode, a first pair of opposed deflection plates, a second pair of opposed deflection plates disposed at right angles to said first pair, and a collector electrode structure, spaced along the longitudinal axis of said envelope in that order and defining 'a beam path, said collector electrode structure including a planar electrode normal to the beam'path and having a first aperture located adjacent the beam path and a pair of apertures on opposite sides of the beam path and said first aperture and so disposed that the outer edge of one aperture is spaced from said path substantially the same distance as the inner edge of the other aperture, a collector electrode positioned beyond said planar electrode in position to receive electrons through said first aperture, means connecting .said collector electrode to one of said second pair of deflection plates for applyinga deflecting potential thereto during operation of said device, collector electrode means positioned beyond said planar electrode in position to receive electrons through said pair of apertures, and means connecting said collector electrode means to one of said first pair of deflection plates for applying a stabilizing potenial thereto during operation of said device.

HARRY C. THOMPSON.

REFERENCES CITED The following references are of record in the 

